The build-up of plaque in blood vessels is common and causes may life-threatening events, such as heart attacks and strokes. Atherosclerotic plaque, for example, is known to accumulate in arterial walls of the human body. This plaque build-up restricts circulation and can result in cardiovascular problems, particularly when the build-up occurs in coronary arteries.
A method for opening a partially occluded blood vessel is to guide one or more medical devices to a diseased, e.g., occluded, site where they can be used to carry out treatment. A guidewire is often used for guiding a catheter or other treatment device toward the diseased site. The distal tip of the guidewire can be introduced into the body of a treated subject by means of a needle or other access device, which pierces the subject's skin, and advanced to the site. The catheter or other treatment device can then be threaded over the guidewire and advanced through internal blood vessel passages to the diseased site using the guidewire as a rail.
Total or near-total occlusions can block passage through portions of a blood vessel. In subjects suffering from a coronary chronic total occlusion (CTO), for example, successful treatment of the occlusion can be challenging. A factor that can determine whether a user, e.g., a treating clinician, can successfully treat the occlusion is the clinician's ability to advance a guidewire from a location proximal of the occlusion to a location distal of the occlusion. In some instances, such as when the occlusive matter is soft or where the occlusion has a tiny opening, the guidewire can be forced through the occlusive matter and allowed to remain within the natural or true lumen of the blood vessel. In other instances, such as when the true lumen of the blood vessel is totally occluded by hard plaque (e.g., calcified atherosclerotic plaque), the guidewire cannot cross the occlusion and, in response to a continued proximally-applied pushing force, may permanently kink and/or its distal end portion may deviate to an adjacent vessel wall and perforate the vessel.